The present invention relates to a solid-state image sensor, more specifically a solid-state image sensor having the image quality improved.
The solid-state image sensors using semiconductor are largely classified in the CCD and the CMOS image sensor based on CMOS.
The CMOS image sensor mainly comprises a pixel array part including pixels having photodiodes formed in a matrix, a black pixel array part including pixels shielded from light, an analog circuit part for processing analog signals outputted from the pixel array part, a digital circuit part for processing signals outputted from the analog circuit part, and an input/output circuit part for inputting and outputting signals to and from the outside. The black pixel array part is for ensuring a reference level of black color.
The CMOS image sensor is much noted because of the much lower electric power consumption than the CCD.
Following references disclose the background art of the present invention.
[Patent Reference 1]
Specification of Japanese Patent Application Unexamined Publication No. 2002-329854
[Patent Reference 2]
Specification of Japanese Patent Application Unexamined Publication No. Hei 11-317667/1999
However, the conventional CMOS image sensor has not been always able to have good image quality.